1. Field of the Invention
This invention relates generally to light transmitting adhesive materials for bonding transparent laminates, and is more particularly concerned with an electron discharge device having a transparent portion of an evacuated envelope bonded to a transparent panel by an interposed adhesive layer of stabilized light transmissive material.
2. Discussion of the Prior Art
An electron discharge device may comprise a cathode ray tube having an evacuated envelope wherein an electron gun is disposed to direct an electron beam onto a spaced anode target. The target may be supported adjacent a transparent faceplate portion of the envelope, and include an imaging screen layer of phoshor material which flouresces locally when a discrete region thereof is penetrated by beamed electrons. Consequently, the tube usually is provided with electron focussing means for directing the electron beam onto a discrete area of the imaging screen layer. Also, the tube is provided with deflection means for causing the focussed electron beam to scan over successive areas of the imaging screen layer in a line-by-line raster pattern. Thus, by suitably modulating the intensity of the scanning electron beam, informational data may be electronically "written" on the imaging screen layer to obtain a visible light display, which may be viewed visually through the adjacent faceplate portion of the envelope.
For safety purposes, a transparent implosion panel usually is bonded to the exterior surface of the faceplate portion by an interposed layer of visible radiation transmissive material, which usually comprises an epoxy resin mixed with a curing agent. Thus, the visible light display produced by the imaging screen may be viewed through the transparent implosion panel, the visible light transmissive material of the bonding layer, and the transparent faceplate portion of the envelope. However, it is generally found, particularly when the tube is operated at relatively high temperatures, that the material of the bonding layer darkens, thereby degrading the visible light transmissive properties of the bonding material correspondingly. As a result, the informational data displayed by the imaging screen within the envelope becomes obscured, thus frustrating the purpose of operating the tube.
Therefore, it is advantageous and desirable to provide a cathode ray tube with stabilized light transmissive means for bonding the implosion panel to the faceplate portion of the envelope.